Recently we applied this optimization to metrics observer and time
used by its method dropped from 12m to 3m for us1 (220m segments).
It looks that it make sense to apply the same code to all observers.
Change-Id: I05898aaacbd9bcdf21babc7be9955da1db57bdf2
Current tally is calculating storage both for buckets and
storage nodes. This change is moving nodes storage
calculation to separate service that will be using
segment loop.
Change-Id: I9e68bfa0bc751c82ff738c71ca58d311f257bd8d